IVAS 2022 banner
IVES 9 IVES Conference Series 9 IVAS 9 IVAS 2022 9 The kinetics of grape aromatic precursors hydrolysis at three different temperatures

The kinetics of grape aromatic precursors hydrolysis at three different temperatures

Abstract

In neutral grapes, it is known that most aroma compounds are present as non-volatile precursors. There is strong evidence that supports the existence of a connection between the content of aroma precursors in grapes and the aromatic quality of wine1. Harsh acid hydrolysis is considered the better way to reveal the aroma potential of winemaking grapes, because transformations taking place during fermentation include relevant chemical rearrangements in acid media that are better predicted by acid hydrolysis2. The aim of the present work is to establish a methodology to evaluate the aromatic potential of the grape from the acid hydrolysis in anoxic conditions of its aromatic and phenolic fraction.
In this work, firstly two different samples of Grenache grapes aromatic and phenolic fraction (PAF) were extracted, followed by acid hydrolysis under strict anoxic conditions based on a previously developed methodology3. These PAFs were reconstituted in model wine and aged in duplicate under anoxic conditions at three temperatures: 75, 50 and 35 ºC. The aged model wines were collected at different sampling times 75 ºC (1h, 2h, 6h, 12h, 24h, 48h, 96h), 50 ºC (0.5, 1, 2, 5, 7, 10 and 14 weeks) and at 35ºC (0.5, 1, 5, 3.5, 6, 9 and 12 months).
Hydrolysates were extracted and analyzed by two different analytical methods: esters, free norisoprenoids, terpenoids, phenols, lactones, vanillins and cinnamates were analyzed by SPE-GC-MS4, while varietal thiols were analyzed by LC-QqQ-MS.
The hydrolysates obtained at 50 and 75ºC present sensory profiles congruent with olfactory nuances of unoxidized wine. In fact, the absolute concentration values ​​found for terpenes, lactones and norisoprenoids are within the normal values ​​expected in a wine, except for TDN, which appears in large quantities. However, phenols, derivatives of vanilla and varietal thiols especially 3-mercaptohexanol appear in much higher amounts than would be expected in a Grenache wine, possibly because this type of hydrolysis is capable of release a major part of aromatic potential of grape. Very few differences are observed in the hydrolysis profiles between the two samples. The hydrolysis profile at the same temperature is similar between the samples in most cases even though different amounts of volatiles are obtained. All compounds seem to hydrolyze following two types of behavior that can be explained by the combination of two phenomena: the generation of volatiles (hydrolysis and rearrangements) and the subsequent degradation at wine pH. For those compounds with congruent evolutions at the three different temperatures, a model able to predict the evolution of varietal volatiles at room temperature will be presented.

DOI:

Publication date: June 24, 2022

Issue: IVAS 2022

Type: Poster

Authors

Sánchez Acevedo Elayma1, Lopez Ricardo1 and Ferreira Vicente1

1Laboratory for Aroma Analysis and Enology (LAAE), Universidad de Zaragoza, Instituto Agroalimentario de Aragón (IA2) (UNIZAR-CITA), Zaragoza (Spain)

Contact the author

Keywords

aromatic and phenolic fraction (PAF), acid hydrolisis, aroma

Tags

IVAS 2022 | IVES Conference Series

Citation

Related articles…

Copper contamination in vineyard soils of Bordeaux: spatial risk assessment for the replanting of vines and crops

Copper (Cu) is widely and historically used in viticulture as a fungicide against mildew. Cu has a strong affinity for soil organic matter and accumulates in topsoil horizons. Thus, Cu may negatively affect soil organisms and plants, consequently reducing soil fertility and productivity. The Bordeaux vineyards have the largest vineyard surfaces (26%) within French controlled appellation and a great proportion of French wine production (around 5 million hl per year). Considering the local context of vineyard surfaces decreasing (vine uprooting) and possible new crop plantation, the issue of Cu potential toxicity rises. Therefore, the aims of this work are firstly to evaluate the Cu contamination in vineyard soils of Bordeaux, secondly to produce a risk assessment map for new vine or crop plantation. We used soil analyses from several local studies to build a database with 4496 soil horizon samples. The database was enhanced by means of pedotransfer functions in order to estimate the bioaccessible (EDTA-extractable) Cu in soils of samples without measurements. From this database, 1797 georeferenced samples with CuEDTA concentrations in the topsoil (0-50 cm depth) were used for kriging interpolation in order to produce the spatial distribution map of CuEDTA in vineyard soils. Then, the spatial distribution of Cu was crossed with vine uprooting surfaces and municipality boundaries. CuEDTAconcentrations ranged from 0.52 to 459 mg/kg and showed clear anomalies. Our results from spatial analysis showed that almost 50% of vineyard soil surfaces have CuEDTA concentrations higher than 30 mg/kg (moderate risk for new plantation) and 20% with concentrations higher than 50 mg/kg (high risk for new plantation). A decision-support map based on municipalities was realised to provide a simple tool to stakeholders concerned by land use management.

Grapevine yield-gap: identification of environmental limitations by soil and climate zoning in Languedoc-Roussillon region (south of France)

Grapevine yield has been historically overlooked, assuming a strong trade-off between grape yield and wine quality. At present, menaced by climate change, many vineyards in Southern France are far from the quality label threshold, becoming grapevine yield-gaps a major subject of concern. Although yield-gaps are well studied in arable crops, we know very little about grapevine yield-gaps. In the present study, we analysed the environmental component of grapevine yield-gaps linked to climate and soil resources in the Languedoc Roussillon. We used SAFRAN data and IGP Pays d’Oc wine yields from 2010 to 2018. We selected climate and soil indicators proving to have a significant effect on average wine yield-gaps at the municipality scale. The most significant factors of grapevine yield were the Soil Available Water Capacity; followed by the Huglin Index and the Climatic Dryness Index. The Days of Frost; the Soil pH; and the Very Hot Days were also significant. Then, we clustered geographical zones presenting similar indicators, facilitating the identification of resources yield-gaps. We discussed the number of zones with the experts of IGP Pays d’Oc label, obtaining 7 zones with similar limitations for grapevine yield. Finally, we analysed the main resources causing yield-gaps and the grapevine varieties planted on each zone. Mapping grapevine resource yield-gaps are the first stage for understanding grapevine yield-gaps at the regional scale.

Mesoclimate impact on Tannat in the Atlantic terroir of Uruguay

The study of climate is relevant as an element conditioning the typicity of a product, its quality and sustainability over the years. The grapevine development and growth and the final grape and wine composition are closely related to temperature, while climate components vary at mesoscale according to topography and/or proximity to large bodies of water. The objective of this work is to assess the mesoclimate of the Atlantic region of Uruguay and to determine the effect of topography and the ocean on temperature and consequently on Tannat grapevine behavior.

Current climate change in the Oplenac wine-growing district (Serbia)

Serbian autochthonous vine varieties Smederevka (for white wines) and Prokupac (for rosé and red wines) are the primary representatives of typical characteristics of wines and terroir of numerous wine-growing areas in Serbia. In the past, these varieties were the leading vine varieties, however, as the result of globalization of winemaking and the trend of consumption of wines from widely prevalent vine varieties, they were replaced by introduced international varieties. Smederevka and Prokupac vine varieties are characterized by later time of grape ripening, and relative sensitivity to low temperatures. Climate conditions can be a restrictive factor for production of high-quality grapes and wine and for the spatial spreading of these varieties in hilly continental wine-growing areas.
This paper focuses on the spatial analysis of changes of main climate parameters, in particular, analysis of viticultural bioclimatic indices that were determined for the purposes of viticulture zoning of wine-growing areas in the period 1961-2010, and those same parameters determined for the current, that is, referential climate period (1988-2017). Results of the research, that is, analysis of climate changes indicate that the majority of examined climate parameters in the Oplenac wine-growing district improved from the perspective of Smederevka and Prokupac vine varieties. These studies of climate conditions indicate that changes of analyzed climate parameters, that is, bioclimatic indices will be favorable for cultivation of varieties with later grape ripening times and those more sensitive to low temperatures, such as the autochthonous vine varieties Smederevka and Prokupac, therefore, it is recommended to producers to more actively plant vineyards with these varieties in the territory of the Oplenac wine-growing district.

Modeling island and coastal vineyards potential in the context of climate change

Climate change impacts regional and local climates, which in turn affects the world’s wine regions. In the short term, these modifications rises issues about maintaining quality and style of wine, and in a longer term about the suitability of grape varieties and the sustainability of traditional wine regions. Thus, adaptation to climate change represents a major challenge for viticulture. In this context, island and coastal vineyards could become coveted areas due to their specific climatic conditions. In regions subject to warming, the proximity of the sea can moderate extremes temperatures, which could be an advantage for wine. However, coastal and island areas are particular prized spaces and subject to multiple pressures that make the establishment or extension of viticulture complex.
In this perspective, it seems relevant to assess the potentialities of coastal and island areas for viticulture. This contribution will present a spatial optimization model that tends to characterize most suitable agroclimatic patterns in historical or emerging vineyards according to different scenarios. Thanks to an in-depth bibliography a global inventory of coastal and insular vineyards on a worldwide scale has been realized. Relevant criteria have been identified to describe the specificities of these vineyards. They are used as input data in the optimization process, which will optimize some objectives and spatial aspects. According to a predefined scenario, the objectives are set in three main categories associated with climatic characteristics, vineyards characteristics and management strategies. At the end of this optimization process, a series of maps presents the different spatial configurations that maximize the scenario objectives.